Drug abuse epidemiology - Research lines

Estimation of heroin and cocaine use incidence trends in Spain.

Objectives: To estimate incidence trends for heroin and cocaine use in Spain. Methodology: The project is a study to analyse data already collected in a data base from a national information system: the treatment demand indicator from the “Sistema Estatal de Información sobre Toxicomanías” (SEIT). The study population are opiate and cocaine users that started at least one treatment episode at centres included in SEIT. Records are anonymous and, since 1991, there is a variable allowing to distinguish between first and subsequent admissions into treatment. Log-linear models were applied for incidence estimation of each substance in order to reconstruct incomplete onset frequency tables because they were out of the study period. A distribution of the period of time between first onset to first treatment, called “Latency Period” (LP), was calculated and analysed.

Results: Incidence of heroin use showed its maximum between 1979 and 1982 with a rate between 2 and 3 individuals / 1.000 inhabitants (IC95%: 2-3), later it decreased rapidly until 1993, was smoother until 2002 and later more or less stable until 2005. On the other side, for cocaine, incidence shows a slow increase since 1978, more rapid by the middle of the 90’s, arriving in 2004 to a rate of 5 individuals / 1.000 inhabitants (IC95%: 3-7). The LP distribution shows that 50% of heroin users delay up to 3 years to start their first treatment, while for 50% of cocaine users this delay is up to about 19 years.

Status. The analyses are complete in both substances, whose results were presented in national conferences, in the Spanish Drug Observatory and in the EMCDDA. Nowadays, papers are being prepared for their publication.

Validation study of the SDS, CAST and DSM-IV-Abuse scales among young cannabis consumers.

Aims:

To validate three scales, adapted in the context of Spanish school surveys, for assessing the severity of cannabis use among young people in Spain.

To detect dual diagnoses, according to DSM-IV criteria, among young cannabis consumers.

Methods: This is a cross-sectional study with 180 healthy volunteers aged 18 to 25 years, who have consumed cannabis in the last 12 months. They will be administered the SDS (Severity Dependence Scale), the CAST (Cannabis Abuse Screening Test), the Abuse-IV questions (5 questions to collect DSM-IV abuse criteria), and the PRISM (Psychiatric Interview for Substance and Mental Disorders). Other variables to be collected include: demographic variables, toxicological history, consumption patterns. Analysis of metric properties and questionnaire conceptual models. Reliability: Cronbach alpha, and Kappa index for test-retest. Construct validity: chi-squared test. Criteria validity: analysis of the areas under ROC curves and chi-squared test for the various scale cut-off points, taking DSM-IV diagnoses obtained through PRISM as the gold standard.

Results: NON AVAILABLE

Status: Interviewing subjects.

Estimation of cannabis and cocaine use incidence trends in Spain.

To study Spanish incidence trends of cannabis use from two existing sources: A) general population surveys about drug use (EDADES) and B) first treatment onset episodes for cannabis use extracted from the indirect indicator of treatment admissions from the Spanish Drug Observatory (OED).

To study incidence trends of cocaine use in Spain from A) EDADES.

Methodology:

From EDADES data bases (biannual between 1997-2005), information reported by subjects that had ever used cannabis or cocaine will be collected.

From the OED‘s main treatment data base between 1996 and 2005, subjects that started at least one treatment episode at centres included in the SEIT with cannabis as the main drug will be selected. Year of cannabis use onset will be necessary to calculate the latency period (LP) which is the time between first cannabis use and first treatment admission for that substance.

To analyse:

(A) Annual incidences for cannabis and cocaine use from people who declared to have used them ever in lifetime will be reconstructed, separately for each drug. Weights for each Spanish region and age and gender groups will be restored taking into account data sampling in the different surveys.

(B) Spanish cannabis use incidence estimation will be approached through a log-linear model with two dimensions: years of onset and LP length in years. To estimate it by Spanish regions or other variables, the data base will be stratified by these variables. In this case, the log-linear model will not be feasible and the Back-Calculation method will be probably chosen, in which case incidence is estimated through aggregated data by treatment admission year and an appropriate LP parametric distribution.